It wasn’t that long ago when smartphones that could transmit video and self-driving cars were pure science-fiction. Although self-driving cars are still in their infancy, smartphones (or cellphones, for that matter) have quietly crept into our lives, and most of us don’t know what we did before them.

Home robots once only existed in the sci-fi world, too, but more capable home robots seem just around the corner. And the evolution of the transistor has played a major role in getting robots to this point.

Before, perhaps the 1950s, many of the most interesting inventions in the world were primarily mechanical that involved comparatively simple electronics. After that time, however, things began to shift with the invention of the transistor.

One could argue the transistor is the most transformative inventions ever. Ironically, most wouldn’t be able to name AT&T physicists John Bardeen, Walter H. Brattain, and William B. Shockley as the people who are generally credited with creating the technology that permeates what you’re now reading this article on.

The first transistor was something along the lines of a baseball in size. Early commercial models, like the TO-3, designed in the mid-1950s and designed to fit into a socket for a vacuum tube, were quite large by today’s standards. They are still available to purchase if you need one.

In 2014, the best Intel processor available had 1.7 billion transistors. Making the very rough assumption that ten 1950s-era TO-3 transistors, if stripped of their housings, could fit into the same area as a modern chip, that is a 170 million percent improvement-170,000,000 percent-in transistor density. This doesn’t even account for the 18 months that Intel has had to improve on early 2014 designs, but what is a few tens of millions of transistors in the grand scheme of things?

The inventors of the transistor (left to right), John Bardeen, William Shockley and Walter Brattain, at Bell Labs in 1948. (Photo Credit: AT&T/Jack St via Wikipedia)

For most applications, perhaps a few million transistors doesn’t actually matter that much at this point. A five-year-old PC will still open Word or stream Netflix, and maybe we are getting to the point where speed isn’t as important as cost for many applications.

For example, Raspberry Pi boards are available for $5, and the C.H.I.P. computer is available for $9 (though both may be tough to find at those claimed prices). Add to this that data processing chips like the ATtiny are available for much less, and you’ve got a recipe for robotics everywhere, or the over-used catchphrase Internet of Things (IoT). Though interesting at $10, no one would want an IoT device if it meant spending $1000 to monitor your dryer’s settings.

Besides simple appliance monitoring, this scaling down both in price and size has led to some excellent applications for home use. Robot vacuum cleaners, like iRobot’s Roomba or Dyson’s 360 Eye, are perhaps the most well-known home robots, followed by a few attempts at lawn mowers. Though not robots in the traditional arms-and-legs sense, smartphones can act as virtual assistants, and as a hub for other simpler robotic appliances.

Of course, kids love automated transistor-based toys. These come in the form of simple trucks or animals that sing, growl, and light up, or even things that could fully be considered robots in their own right. Here’s a list of several robot toys that should keep kids entertained (and hopefully learning) for hours. Though these robots can have an incredible array of abilities, they generally fall in the $100-$150 price range.

So the next time you use your phone, or see your kids playing with their robot toys, remember someone had to invent what powers it. Thousands more had to improve on this invention until we got robots at a size and price that would certainly have been unbelievable even to science fiction writers when the transistor emerged.